The present invention relates to removal and treatment of a surface layer of liquid which floats atop another liquid, and in particular to the removal and treatment of a surface layer of an oil or oil-like substance from a contained body of an aqueous solution.
Oil-water mixtures are generated as a result of various activities, and a major source of such mixtures is industrial activity. For a number of reasons, it is desirable to separate the oil from such mixtures. Environmentally, it is desirable to limit the amount of pollution resulting from the discharge of such mixtures resulting from the sites of such industrial activity; it is preferable to recycle and reuse the oil and water components of the mixtures. Economically, it is often desirable to continue to utilize a solution in which an oil becomes a contaminant, as such solutions typically contain a number of additives which are expensive. It is also desirable to remove an oil contaminant so that a particular industrial process may proceed under conditions which are as clean and uncontaminated as possible, thus improving both the manufacturing process and workplace health and safety.
For example, many machine parts or heat treated parts are washed in parts washing tanks, resulting in the washing solution becoming contaminated with manufacturing oils and heat treating quench oils. Although in the past, this contaminated wash water was discharged into the sewage system, it became necessary to haul the oil-contaminated wash water away to disposal sites or to treatment sites for further separation. Oily contamination in the parts washing solutions contributes to an inefficient cleaning process which typically requires secondary cleaning and manufacturing steps to correct, which then result in added time and expense. The contaminating oil in parts washers is often carried into subsequent heat treating tempering furnaces where the oil burns off as smoke in the plant which is then discharged into the local environment. Moreover, the presence of the oily contaminant also endangers the health and safety of the plant workers. Not only is the in-plant smoke a danger, but frequent changes of washing baths due to oil contamination require increased worker exposure to cleaning fluids and related handling hazards.
Several types of treatment methods and systems have been developed in efforts to efficiently separate oil from oil-water mixtures. Typically, these involve a means to remove a fraction of the mixture which is enriched in oil, and a means to further separate the oil from this fraction. The removal means are typically skimmers, which skim a fraction enriched in the oil from an oil-water mixture. Many different types of skimmers are known; these include belt skimmers, disk skimmers, drum/barrel skimmers, mop skimmers, tube skimmers, and floating suction skimmers. The separation means vary, and include from one to several of the following: filtration separation, gravity separation, including vertical and horizontal separators, and coalescing separators, which include tightly packed beds of plates, helical coalescers, and gas bubbles.
These treatment systems are utilized in a variety of situations, which range from open water to boat marinas to tanks in industrial plants. Although they vary in their details, they share several features in common: they are designed to be used for large volumes of oil-water mixtures with large surface areas, and to be used continuously. Thus, these systems are generally large, heavy, and relatively immobile as they are fixed in place, and then operated continuously.
However, there are many situation in which such large, immobile systems are less than ideal. Such situations include multiple small volumes of mixtures, each in small tanks, and tanks with obstacles protruding from the surface. Such obstacles include mechanical apparatus supporting the tank""s purpose, including sprann and immersion hardware. In these situations, it would be desirable to collect and treat accumulated oil in the surface layer in batches, rather than continuously. It would also be desirable to have an oil-water mixture treatment system which is mobile, for use with multiple mixtures, as would exist in multiple tanks. It would also be desirable to have a collection means which is manually controlled, for maneuverability across a surface and around surface protruding obstacles in the oil-water mixture.
It is an object of the present invention to provide a method of collecting an oil contaminant from the surface of a solution where the solution is contaminated as a result of an industrial activity, and where the method is easily and advantageously used in the industrial setting and can be employed for multiple tanks and in a batch mode. It is a further object to provide a system for collecting and treating such an oil contaminant from the surface of a solution, where the system is lightweight and mobile, and can be easily deployed among multiple tanks of different configurations and locations.
These and other objects are met by the present invention. In some aspects, the present invention provides a method for removing a layer of an oil contaminant from the surface of an aqueous solution, comprising providing a solution contaminated by oil as a result of an industrial activity, and a surface skimmer which can be manually controlled from a remote location; and manually controlling the surface skimmer to remove a layer of oil by the skimmer. In other aspects, the present invention provides a method for removing a batch of an oil contaminant from the surface of an aqueous solution, comprising providing a solution contaminated by oil as a result of a manufacturing process, and a surface skimmer which can be manually controlled from a remote location, and manually controlling the surface skimmer to remove a layer of oil by the skimmer for a sufficient time to remove a batch of oil.
In certain embodiments of both aspects, the industrial activity is selected from the group consisting of parts cleaning and washing, cutting and grinding, die casting, metal plating, heat treating, surface finishing, pressure washing, steam cleaning, cooling, lubricating, cleaning, and food processing. In other embodiments of both aspects, the solution is enclosed in a tank at a location of the industrial activity. In yet other embodiments of both aspects, the oil comprises hydraulic oils, surface finishing oils, quench oils, way oils, cutting, grinding and hobbing oils, and oils derived from food sources. In yet other embodiments, the method further comprises separating the aqueous solution from the oil contaminant removed from the solution surface. In a preferred embodiment of both aspects, the method further comprising separating the aqueous solution from the oil contaminant removed from the solution surface, wherein the industrial activity is selected from the group consisting of parts cleaning and washing, cutting and grinding, die casting, metal plating, heat treating, surface finishing, pressure washing, steam cleaning, cooling, lubricating, cleaning, and food processing, wherein the solution is enclosed in a tank at a location of the industrial activity, wherein the oil comprises hydraulic oils, surface finishing oils, quench oils, way oils, cutting, grinding and hobbing oils, and oils derived from food sources.
The present invention also provides a system for removing a layer of an oil contaminant from the surface of an aqueous solution, comprising a surface skimmer, a collection means, a conduit connecting the skimmer to the collection means in an airtight fashion, and means for creating negative pressure in the skimmer, where the skimmer capable of manual control from a remote location, and where the solution is contaminated as a result of an industrial process. In one aspect of the present invention, the system can be used to remove a surface layer of an oil contaminant; in another aspect, the system is used to remove a batch of a surface layer of an oil contaminant. In one embodiment of both aspects, the skimmer is lightweight and portable. In another embodiment of both aspects, the collection means is lightweight and mobile. In yet another embodiment of both aspects, the collection means is a vertical separator. In a preferred embodiment of both aspects, the skimmer is lightweight and portable, and the collection means is lightweight and mobile and a vertical separator.
The present invention also provides a device for removing a layer of an oil contaminant from the surface of an aqueous solution, comprising a surface skimmer, a collection means, a conduit connecting the skimmer to the collection means in an airtight fashion, and means for creating negative pressure in the skimmer, wherein the skimmer capable of manual control from a remote location and comprises a hollow tube with two ends and two openings. The first opening is a skimmer inlet, such that the inlet is an opening cut horizontally along the tube, and close to a first end which is closed, and the second opening is a skimmer outlet, and is a second end which is open and which can be connected to the conduit.
The present invention also provides a device for removing a layer of an oil contaminant from the surface of solution, comprising a surface skimmer, a collection means, a conduit connecting the skimmer to the collection means in an airtight fashion, and means for creating negative pressure in the skimmer, where the skimmer capable of manual control from a remote location. The skimmer comprises a hollow tube with two ends and two openings, where the first end of the tube is partially closed and comprises an inlet, and where the inlet extends along the tube from the partially closed first end. The second end of the tube is open and comprises an outlet. The tube is also angled between the first and the second end. In a preferred embodiment, the tube is angled at a right angle. In another preferred embodiment, the skimmer further comprises a handle by which the skimmer can be remotely controlled.